didn't realise from the sketch that the columns were different heights, (sloped roof between columns) -my bad- ....Same quick methods can be used, but push/pull from roof face rather than column. (so perpendicular to roof face) Then just trim length of beam to intersect columns..... (you could do all of this by input dimensions if you wanted)

didn't realise from the sketch that the columns were different heights, (sloped roof between columns) -my bad- ....Same quick methods can be used, but push/pull from roof face rather than column. (so perpendicular to roof face) Then just trim length of beam to intersect columns..... (you could do all of this by input dimensions if you wanted)

I would simply snap a guide to the segment you want to be parallel (the roof) and then move it to an appropriate location on the column, or you can draw the new beam against the roof and them move the beam later, there's lots of choices with the flexibility in FormZ. Then draw a line using the 3d wall tool with the new beam thickness from one column to the other. Define a height. Now you'll just need to adjust/extend the ends to penetrate the column and subtract the overlap if you like clean geometry. It's also easy to adjust your new beam thickness and height, while keeping everything parallel and tight.